1. Field of the Invention
The present invention relates to a touch panel and a related device and method, and more particularly, to a touch panel having unbalanced conductive patterns and a related device and method capable of determining multi-touch positions.
2. Description of the Prior Art
In today's consumer electronics markets, portable electronic products such as personal digital assistants (PDAs), mobile phones, and PDA phones have already adopted a touch panel as their interface tool for data communication. Traditional touch panels mainly include resistive touch panels and capacitive touch panels. The resistive touch panel orientates touch positions based on its voltage drops. The capacitive touch panel is usually equipped with sensing capacitors, and it senses touch positions by making use of capacitance variations of the sensing capacitors corresponding to touched points together with an interlaced scanning method including scanning along the horizontal direction (i.e., the X direction) and the vertical direction (i.e., the Y direction).
If there are two fingers simultaneously touching the traditional capacitive touch panel, a problem of wrong reporting of coordinates may happen. A majority of reasons leading to the traditional capacitive touch panel to wrong reporting of coordinates are resulted from the conductive patterns of the touch panel, such as the conductive patterns composed of indium tin oxide (ITO) or indium zinc oxide (IZO). Please refer to FIG. 1. FIG. 1 is a diagram showing symmetrical conductive patterns of a traditional touch panel in the prior art. The touch panel usually includes a transparent conductive layer 100, which is formed on a substrate by performing a photo engraving process (PEP). In FIG. 1, the transparent conductive layer 100 comprises a plurality of groups of first conductive patterns 160, a plurality of groups of second conductive patterns 170, a plurality of first wires 130, and a plurality of second wires 140. Each group of first conductive patterns 160 is arranged along a first direction 110 (e.g. the Y direction), each group of second conductive patterns 170 is arranged along a second direction 120 (e.g. the X direction), wherein each group of first conductive patterns 160 and each group of second conductive patterns 170 are electrically insulated to each other (not shown). Furthermore, each first wire 130 is used for electrically connecting the plurality of first conductive patterns 160 located on an identical group to each other (such as the first conductive patterns 160 located on the same column); and each second wire 140 is used for electrically connecting the plurality of second conductive patterns 170 located on an identical group to each other (such as the second conductive patterns 170 located on the same row).
As shown in FIG. 1, each of the first conductive patterns 160 has the same area, and each of the second conductive patterns 170 also has the same area. That is to say, the traditional capacitive touch panel has symmetrical conductive patterns, wherein each of the first conductive patterns 160 and each of the second conductive patterns 170 have the same area. The capacitance variations of the traditional capacitive touch panel are directly proportional to the touched area by the fingers, and the traditional capacitive touch panel senses touch positions row-by-row and column-by-column. Therefore, we should be able to know the cross-points located on which row and which column fingers have touched, but we are unable to know which points fingers have touched. For example, assume that the touched points are (X1, Y2) and (X2, Y1). However, the recognition system of the traditional capacitive touch panel is unable to differentiate the differences between these cross-points (X1, Y2), (X2, Y1) and (X1, Y1), (X2, Y2). It may respond wrong coordinates (X1, Y1) and (X2, Y2).